What is the difference between a-la-carte only sponsor registration and tiered sponsor registration?

With tiered sponsorships, you can link sponsor tiers with particular privileges. You can offer additional features as a benefit from a special or higher tier. For instance, you can offer sponsors in the Gold Tier the ability to schedule one-on-one meetings with attendees or highlight them in every announcement or your registration page via advanced sponsor banner. Having this opportunity available leads to successful participation from both parties. If you choose to set up sponsor registration with tiered sponsorships, you can also offer additional a-la-carte items; however each sponsor must select one tier.

A-la-carte sponsorships provide sponsors with packages that offer very specific features. Each sponsor can select however many sponsorship opportunities they would like. For example, if you offer outreach campaigns as an a-la-carte add-on, sponsors who purchase that item will have access, while all other sponsors can manually send messages and have the daily limit (for spam purposes).